There are different kinds of urinary dysfunction that prevent a patient from maintaining normal control of the flow of urine in the patient's urethra, ureter, renal pelvis or bladder. For example, overflow incontinence, stress incontinence and urge incontinence. (The term “patient” generally includes human beings, but may also include animals.)
Overflow incontinence involves disability of controlling the muscle that contracts the urine bladder. In particular partially paralysed patients may suffer from this condition. Stress incontinence involves disability to keep the urethral sphincter completely closed. In a urinary stress incontinent patient the urethral sphincter is unable to prevent urine from being expelled from the bladder during transient increase in intra-abdominal pressure, which can be caused by sneezing, coughing or laughing, or by lifting heavy goods. Urge incontinence involves spontaneous activity of the bladder causing a compelling feeling of the patient that the bladder needs to be emptied, although the bladder maybe contains little urine.
Urinary stress and urge incontinences are widespread diseases. Although some people suffering from these diseases are helped through training of the muscles in the pelvic floor, too many have severe problems with urine leakage. Many different implant devices have been tried to remedy this kind of urinary incontinence. For example, there is a prior manually operated urinary incontinence treatment apparatus having an artificial hydraulic sphincter device engaging the urethra and connected to an elastic reservoir implanted in the scrotum or in the region of the labia majora. A disadvantage of this prior apparatus is that over time hard fibrosis is developed around the reservoir, which may cause malfunction of pumping components. Furthermore, it is a rather complicated task to manually squeeze the elastic implanted reservoir to pump hydraulic fluid to open the sphincter device when the patient needs to urinate. In particular women can get their fingers wet. The created fibrosis will sooner or later become a hard fibrotic layer, which may make it even more difficult to pump the reservoir. Yet a further disadvantage is that the use of hydraulic fluid always entails a risk of fluid leaking from implanted hydraulic components.
A prior hydraulic apparatus designed to compress the urethra is disclosed in U.S. Pat. No. 5,520,606. A prosthetic sphincter with an inflatable cuff, which surrounds the urethra or encloses it on two sides, is disclosed in for example U.S. Pat. Nos. 4,571,749 and 4,222,377. U.S. Pat. No. 4,969,474 discloses a hydraulic method for treating both men and women having urinary stress incontinence in the same way. The apparatus of U.S. Pat. No. 4,969,474 includes a reservoir containing fluid and an inflatable compression means designed to compress the urethra without risking tissue loss or necrosis to occur. An artificial hydraulically operated urethral sphincter employing an external magnet to achieve closure of the urethral cuff is disclosed in U.S. Pat. No. 5,562,598.
A prior mechanical prosthetic sphincter disclosed in U.S. Pat. No. 4,619,245 comprises a manually controllable actuating component for implanting at a convenient location in the patient's body.
U.S. Pat. No. 4,739,764 discloses a method for treating urinary stress incontinence by electric stimulation of an inferior somatic nerve connected to the urethral sphincter. The function of the urethral sphincter is affected by applying electric pulse trains on the somatic nerve.
U.S. Pat. No. 6,061,596 discloses a system for regularly conditioning and training the pelvic muscles of a urinary stress or urge incontinent patient with electric stimulation so as to restore voluntary control to the patient. The pelvic muscles are stimulated, i.e. conditioned, for 15-60 minutes each day using intermittent trains of electrical pulses. Accordingly, during the rest of each day, i.e. at least 23 hours, the pelvic muscles are not stimulated.
U.S. Pat. Appl. Publication No. 2002/0062060 A1 discloses a urinary stress or urge incontinence treatment device, which is sensor controlled and is normally not in operation unless signals from the sensors indicate a condition that is likely to cause involuntary urine flow. The sensors generate signals responsive to motion or to intravesical or abdominal pressure, or to urine volume in the bladder. The signals from the sensors are indicative of possible incontinence that may occur due to coughing, laughing, or other strain or motion of abdominal muscles.
One general prior solution to the problem of malfunctioning sphincters of a human body has been to implant an artificial sphincter that replaces a malfunctioning sphincter. A variety of artificial sphincters have been used in the past. These artificial sphincters have included cuffs, clamping elements or inflatable bands that are applied externally around the bodily organ that is connected to the malfunctioning sphincter.
For example, U.S. Pat. No. 3,750,194 discloses a hydraulic cuff applied around the urethra of a patient suffering from urinary incontinence. Hydraulic fluid flowing to the hydraulic cuff causes the cuff to squeeze the urethra and restrict fluid flow through it.
U.S. Pat. No. 6,074,341 discloses a mechanical device in the form of a loop member that is applied around a bodily organ to replace the organ's missing or damaged sphincter. The loop member includes a wire which is used to constrict the organ in question to close the lumen therein.
A disadvantage common to all prior artificial sphinters is that hard fibrosis may form around the artificial sphincter over time and may cause malfunction of the artificial sphincter. Thus, the formed fibrosis may sooner or later become a hard fibrotic layer which may make it difficult for the artificial sphincter to work.
Another more serious disadvantage of the prior artificial sphincters if used for replacing malfunctioning urethral sphincters is that the element that constricts, clamps or restricts the urethra may injure the tissue wall of the urethra. Thus, a consequence of the element's constricting action on the urethra is that the element might erode into the urethra over time, and in a worst case, penetrate the constricted wall portion of the urethra. In addition, blood circulation in the constricted tissue wall portion of the urethra is eventually hampered by the pressure exerted by the element, so that poor blood circulation, or worse, no blood circulation results in deterioration of the constricted tissue.
One solution to prevent tissue deterioration due to poor blood circulation could be to apply two or more separately operating constricting elements along respective tissue wall portions of the urethra and operate the elements sequentially, whereby each tissue wall portion would have time to recover, i.e., restore normal blood circulation while one of the other tissue wall portions is constricted. However, an apparatus devised in accordance with this solution would have several disadvantages. First, the apparatus would require a large amount of space, making it impractical to implant. Second, the operation of the apparatus in moving the constricting elements between constricting and non-constricting positions day and night would require a large power supply. Such a large power supply would necessitate the implantation of a very large, high capacity battery and/or a sophisticated system for continuous wireless transmission of energy from outside the patient's body for frequent charging of an implanted rechargeable battery. Thus, because of its large size and high power consumption, the apparatus would be impractical or even unrealistic. Third, a sophisticated control system would be necessary to control the moving elements. Finally, such a complicated apparatus of the type described above would significantly add to the costs of treating a malfunctioning sphincter.
Another solution to the problem of malfunctioning sphincters that has been previously used has been the electric stimulation of the sphincter, to restore its normal function, i.e., the contraction and closing of its associated lumen. This solution would work where the normal sphincteric function is somewhat reduced and has not completely ceased. European patent application 1004330 A1 discloses an example of such a solution, in which electric pulses are delivered to the lower esophageal sphincter of a patient suffering from reflux disease to minimize reflux. However, the esophageal sphincter has to be continuously stimulated with electric pulses to keep it closed, except when the patient eats, which may result in a decreased stimulation effect over time. An even more serious drawback to this solution is that the continuous stimulation over time might cause tissue deterioration due to poor blood circulation.
The use of electric stimula to restore the sphincteric function of a malfunctioning urethral sphincter is only possible if the sphincter responds sufficiently to the stimula, i.e., closes the urethra. In cases where the sphincteric function of a urethral sphincter has completely ceased, or the urethral sphincter has been removed from the patient's body, electric stimulation cannot be employed.
Electric stimulation of urinary organs other than urethral sphincters can only insignificantly affect the flow of urine. For example, it is true that electric stimulation of the urethra affects flow of urine, but could not possibly fully close the relatively stiff urethra, at least not by employing the necessary low stimulation intensities that are harmless to the human body.